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May 28, 1929. J, NIXON 1,715,143

AUTOMATIC SWITCH Filed Oct. 31, 1924 @0770/14 /7 Tgp Im Jnsef'h Nvcun Patented May 28, 1929.

UN I TED-ff TION OF DELAWARE.

The present invention relates to improve# j ments in or relating "to:automaticiswitches" as used. in telephone -systems la'r'idiritfrepari ticularly to improl'ements intheJtbankfcpn-K 7. tact construction infswitclies of' th'eftwo-di' uch 'switches suallylh'ave", ten' vertical steps andt'tnif'rot'ary stepsfso as" to lhaveA access to a total-'M1001 lines".-l lIn," hunting 'operations I rectional type'.Y

:ft-lector switches where lake placeuon the different` levels,'1t*'=1side sirable to provide additional'fajcilittesfori determining howroften all the lines of a particular group are'biisy: For this purpose it has been proposed to provide an additional .set of line and test contacts throughout thc .switches so as to provide for eleven lines instead ot' teu. This has the disadvantage that extra contacts are provided which are not required in switches of the final selector type unless.v two different types ot switch banks are manufactured. It has also been proposed in British Patent No. 2113/13/14 to employ an auxiliary set of contacts adapted to be engaged by the test wiper for this purpose.

i 'lfhe object of the present invention is a coustructional improvement to enable the desired results to be obtained with the minimum ol" expense in conjunction with a switch structure having access to ten sets of line contacts only in a level. This is attained according to the present invent-ion by providing :in ladditional contact only t'or each level et Vthe bank corresponding to the test contacts. 1n a well known construction the c011- nu-i banks are arranged in two parts, one vertically over the other; in one the line contacts are arranged on each side of an insulating sheet and adapted to be wiped over .simultaneously by the rotating pair of lille wipers. In the other the test contacts are single contacts separated by a much thicker insulation so that the distance between contacts correspondsI to the step between dit'- terent levels. A convenient way of carrying out the invention is therefore to substitute for the thick insulation two thin insulations and arrange a metal plate in the form of an arc eoresponding in shape with the insulations .separating the contacts but provided with a tooth slightly offset so as to be in alignment with the test contacts orp the difieren! rows, and placed in a position corresponding to an eleventh contact. This enables in a veryY convenient manner a meter @UTQMATIC site@ i i fnvembei ,1, 1923i.`

tobe'operated everytime all At-he'lines in a group are'bus'yan'd connectionris established with thetinatcontact of a row. The brass strip carrying theelevnth co'ntact is 'conven'iently" Iprovided with a 'soldering vtag to which Athe' meter maylbe idire'c'tly connected.

In order to ,give the "subscriberthe-'busy signal arrangements maybe' employed in con- Junction" with ',ftli'e arrangement above desciibedfsuch as jdes'crribed infthje previously mentioned EPatent`No24;34f3/191 4. f

'-An vembodiment ofjtlliefinvention -is 'shown by way of exainb'legfin"l the -annexed'drawine, in which fig. 1 is a plan view of the bank assembly.

Fig. 2 is a part elevation thereof looking in the direction of the arrow shown in Fig. 1, whilst Fig. 3 is a cr0ss-section on the line 3-3 of Fig. 1.

The bank comprises in the usual manner ten rows of contacts, assembled together with interposed insulation by means of clamping plates 11 and bolts or the like 12. Each contact is extended at the rear to form a soldering-tag portion 13 in well known manner.

According to the invention the insulation between two rows of contacts is formed b v two thin insulating strips 14, instead of tho usual single thick strip, between which is placed a metal plate 15 in the form of an are corresponding in shape with the insulating Strip 14. The upper row of contacts 10 and the lower plate 15, i. e. those nearest the clamping plate 11, are insulated from the latter plates by insulating strips 16. Each plate 15 is provided at its end with an off-set portion as shown in Fig. 2, to form a Contact 17 in line with the contacts 10 and in a position corresponding to an eleventh contact. A soldering contact 18 is advantageously also formed on each plate 15, in order that the meter, which is adapted to operate when the wiper moving over the bank engages the contact 17, i. e. when all the lines connected to the bank are busy, may be directly connected thereto.

The clamping plates 11 are provided with the usual holes 19 in order that t-he bank may be secured to the switch frame. The contacts 10 may be provided with thin insulating strips 20 in addition to the strips 14.

It will thus be appreciated that a very convenient meansvhas bcenproveided for adding to a switchan extra Contact 1n alignment with the test contacts while utilizing the same tools without alteration for the manufacture ofv the other parts which make. up-the Contact'.

banks, at the same time it should be understood that considerable modifications may he made in the constructional details without departing from the spirit of the invention, for instance hy mounting the strips having a contact corresponding. to the eleventh contact on a supporting post and suitablyinsulating the same. l Y

I-Iavinghno'wA particularly described and ascertained .the nature of my said invention. and 1in what manner the same 1s tobe.perr

2, In Iaycontact hankha lplurality of rows or f-l'evels goaindividualf' contacta; a plurality of plates separating said' rows of individual contacts and insulated therefrom, and an of-Lset :projectingpiece oni eachlof fthe metal plates, eachl.pro]acting:piecerinv line 'with a different row of contacts and'at/'theaend thereof=to form an eleventh contact.

3..A test Wiper `contact bank for switches ofthe type used in automatic or semi-automatic teleplhone.systems,` comprising, aipluralityfof rows .or levels .oftest contacts, an arcuate metalstripbetwecn two levels of said test contacts .andinsulated .from Asaid c two line witlithe test .contacts of,.one. of said levcls and in a position correspondingA to an. auxiliary orelevcnth .-position.

Signed byme i at Liverpool,t England, this 14th dayfof4 October, 1924.

JOSEPHNIXON.

levelsby.` two thin insulating strips, and an ofi' set portion. on said 'strip formingacontact in 

